We present a new ab initio approach to calculate the interaction between electrons and holes in periodic crystals and to evaluate the resulting coupled electron-hole excitations. This involves a novel interpolation scheme in reciprocal space in solving the Bethe-Salpeter equation for the two-particle Green's function. We apply this approach to the calculation of the entire optical absorption spectrum, as well as of the energies and wave functions of bound exciton states in GaAs and LiF. Very good agreement with experiment is observed.

• Received 8 June 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.2312